''Radinskya'' is an extinct perissodactyl-like

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

from the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

( Nongshanian

ALMA Alma or ALMA may refer to: Arts and entertainment * ''Alma'' (film), a 2009 Spanish short animated film * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''Alma'' (play), a 1996 drama by Joshua Sobol about Alma ...

). It is named after palaeontologist and perissodactyl expert

Leonard Radinsky Leonard Burton Radinsky (1937–1985) was an American paleontologist and expert in fossil odd-toed ungulates and their relatives. He was professor at the University of Chicago from 1967 until his death, serving as chairman of the Department of Ana ...

who died prematurely in 1985. Before the discovery of ''Radinskya'', palaeontologists speculated on an American origin for the tethythere-perissodactyl

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

that took place during the Paleocene-Eocene transition (around ). The primitive ''Radinskya'' from China made it clear that this radiation began in Asia during the Paleocene, from where it spread to North America, Europe, and Africa during the Eocene. With its enigmatic position at the base of this radiation, ''Radinskya'' is a member of the Chinese Paleocene fauna which includes primitive tethytheres such as '' Minchenella'' and the oldest arsinoitheres; it shares many characters with perissodactyls and some with phenacolophids, but is too primitive to be called either a horse, a rhino, or a tapir. ''Radinskya'' is known only from a partial skull and upper dentition, which makes it difficult to assess its relationships to other fossils. described the upper molars as "quadrate with a rhomboid outline and a weak, π-shaped crown pattern formed by the incipient ectoloph, protoloph, and metaloph (crests on the crowns). This arrangement closely resembles the crown pattern of early perissodactyls, but the strong conules (cusps) and some other characters suggest relationship to phenacolophids" and added that "''Radinskya'' may be the sister taxon of all other

Altungulata Altungulata or Pantomesaxonia (''sensu'' and later authors) is an invalid clade (mirorder) of ungulate mammals comprising the perissodactyls, hyracoids, and tethytheres (sirenians, proboscideans, and related extinct taxa). The name "Pantomesaxo ...

or may be closer to the origin of Perissodactyla than is any

phenacodontid Phenacodontidae is an extinct family of large herbivorous mammals traditionally placed in the “wastebasket taxon” Condylarthra, which may instead represent early-stage perissodactyls. They lived in the Paleocene and Eocene epochs (about 60� ...

." ''Radinskya'' has also been included into the Embrithopoda, treated as an

outgroup Outgroup may refer to: * Outgroup (cladistics), an evolutionary-history concept * Outgroup (sociology), a social group {{disambig ...

to perissodactyls. and Other Nongshanian phenacolophids include '' Yuelophus'', '' Tienshanilophus'', '' Ganolophus'' and the large form '' Minchenella''.

Notes

References

* * * * * * * * {{Taxonbar, from=Q14565733 Prehistoric odd-toed ungulates Fossil taxa described in 1989 Paleocene mammals Paleogene mammals of Asia Prehistoric placental genera